ASTM D 5628 - 18 Standard Test Method for Impact Resistance of Flat, Rigid Plastic Specimens by Means of a Falling Dart (Tup or Falling Mass)

1.1 This test method covers the determination of the threshold value of impactfailure energy required to crack or break flat, rigid plastic specimens under various specified conditions of impact of a freefalling dart (tup), based on testing many specimens.1.2 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements are given in Section 8.NOTE 1: This test method and ISO 66031 are technically equivalent only when the test conditions and specimen geometry required for Geometry FE and the Bruceton Staircase method of calculation are used.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee Designation: D5628 − 18 Standard Test Method for Impact Resistance of Flat, Rigid Plastic Specimens by Means of a Falling Dart (Tup or Falling Mass)1 This standard is issued under the fixed designation D5628; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision A number in parentheses indicates the year of last reapproval A superscript epsilon (´) indicates an editorial change since the last revision or reapproval Scope* D2444 Practice for Determination of the Impact Resistance of Thermoplastic Pipe and Fittings by Means of a Tup (Falling Weight) D3763 Test Method for High Speed Puncture Properties of Plastics Using Load and Displacement Sensors D4000 Classification System for Specifying Plastic Materials D5947 Test Methods for Physical Dimensions of Solid Plastics Specimens D6779 Classification System for and Basis of Specification for Polyamide Molding and Extrusion Materials (PA) E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method 2.2 ISO Standards:3 ISO 291 Standard Atmospheres for Conditioning and Testing ISO 6603-1 Plastics—Determination of Multiaxial Impact Behavior of Rigid Plastics—Part 1: Falling Dart Method 1.1 This test method covers the determination of the threshold value of impact-failure energy required to crack or break flat, rigid plastic specimens under various specified conditions of impact of a free-falling dart (tup), based on testing many specimens 1.2 The values stated in SI units are to be regarded as the standard The values in parentheses are for information only 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use Specific hazard statements are given in Section NOTE 1—This test method and ISO 6603-1 are technically equivalent only when the test conditions and specimen geometry required for Geometry FE and the Bruceton Staircase method of calculation are used 1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee Terminology 3.1 Definitions: 3.1.1 For definitions of plastic terms used in this test method, see Terminologies D883 and D1600 3.2 Definitions of Terms Specific to This Standard: 3.2.1 failure (of test specimen)—the presence of any crack or split, created by the impact of the falling tup, that can be seen by the naked eye under normal laboratory lighting conditions 3.2.2 mean-failure energy (mean-impact resistance)—the energy required to produce 50 % failures, equal to the product of the constant drop height and the mean-failure mass, or, to the product of the constant mass and the mean-failure height 3.2.3 mean-failure height (impact-failure height)—the height at which a standard mass, when dropped on test specimens, will cause 50 % failures Referenced Documents 2.1 ASTM Standards:2 D618 Practice for Conditioning Plastics for Testing D883 Terminology Relating to Plastics D1600 Terminology for Abbreviated Terms Relating to Plastics D1709 Test Methods for Impact Resistance of Plastic Film by the Free-Falling Dart Method This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties Current edition approved May 1, 2018 Published June 2018 Originally approved in 1994 Last previous edition approved in 2010 as D5628 - 10 DOI: 10.1520/D5628-18 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website NOTE 2—Cracks usually start at the surface opposite the one that is struck Occasionally incipient cracking in glass-reinforced products, for example, is difficult to differentiate from the reinforcing fibers In such cases, a penetrating dye can confirm the onset of crack formation Available from American National Standards Institute (ANSI), 25 W 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org *A Summary of Changes section appears at the end of this standard Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959 United States D5628 − 18 5.3.1 The conical configuration of the 12.7-mm diameter tup used in Geometry FB minimizes problems with tup penetration and sticking in failed specimens of some ductile materials 3.2.4 mean-failure mass (impact-failure mass)—the mass of the dart (tup) that, when dropped on the test specimens from a standard height, will cause 50 % failures 3.2.5 tup—a dart with a hemispherical nose See 7.2 and Fig 5.4 The test conditions of Geometry FC are the same as those of Test Method A of Test Method D1709 They have been used in specifications for extruded sheeting A limitation of this geometry is that considerable material is required Summary of Test Method 4.1 A free-falling dart (tup) is allowed to strike a supported specimen directly Either a dart having a fixed mass is dropped from various heights, or a dart having an adjustable mass is dropped from a fixed height (See Fig 2) 5.5 The test conditions of Geometry FD are the same as for Test Method D3763 5.6 The test conditions of Geometry FE are the same as for ISO 6603-1 4.2 The procedure determines the energy (mass × height) that will cause 50 % of the specimens tested to fail (mean failure energy) 5.7 Because of the nature of impact testing, the selection of a test method and tup must be somewhat arbitrary Although a choice of tup geometries is available, knowledge of the final or intended end-use application shall be considered 4.3 The technique used to determine mean failure energy is commonly called the Bruceton Staircase Method or the Upand-Down Method (1).4 Testing is concentrated near the mean, reducing the number of specimens required to obtain a reasonably precise estimate of the impact resistance 5.8 Clamping of the test specimen will improve the precision of the data Therefore, clamping is recommended However, with rigid specimens, valid determinations can be made without clamping Unclamped specimens tend to exhibit greater impact resistance 4.4 Each test method permits the use of different tup and test specimen geometries to obtain different modes of failure, permit easier sampling, or test limited amounts of material There is no known means for correlating the results of tests made by different impact methods or procedures 5.9 Before proceeding with this test method, reference the specification of the material being tested Table of Classification System D4000 lists the ASTM materials standards that currently exist Any test specimens preparation, conditioning, dimensions, or testing parameters or combination thereof covered in the relevant ASTM materials specification shall take precedence over those mentioned in this test method If there are no relevant ASTM material specifications, then the default conditions apply Significance and Use 5.1 Plastics are viscoelastic and therefore are likely to be sensitive to changes in velocity of the mass falling on their surfaces However, the velocity of a free-falling object is a function of the square root of the drop height A change of a factor of two in the drop height will cause a change of only 1.4 in velocity Hagan et al (2) found that the mean-failure energy of sheeting was constant at drop heights between 0.30 and 1.4 m This suggests that a constant mass-variable height method will give the same results as the constant height-variable mass technique On the other hand, different materials respond differently to changes in the velocity of impact While both constant-mass and constant-height techniques are permitted by these methods, the constant-height method is to be used for those materials that are found to be rate-sensitive in the range of velocities encountered in falling-weight types of impact tests Interferences 6.1 Falling-mass-impact-test results are dependent on the geometry of both the falling mass and the support Thus, impact tests are used only to obtain relative rankings of materials Impact values cannot be considered absolute unless the geometry of the test equipment and specimen conform to the end-use requirement Data obtained by different procedures within this test method, or with different geometries, cannot, in general, be compared directly with each other However, the relative ranking of materials is expected to be the same between two test methods if the mode of failure and the impact velocities are the same 6.1.1 Falling-mass-impact types of tests are not suitable for predicting the relative ranking of materials at impact velocities differing greatly from those imposed by these test methods 5.2 The test geometry FA causes a moderate level of stress concentration and can be used for most plastics 5.3 Geometry FB causes a greater stress concentration and results in failure of tough or thick specimens that not fail with Geometry FA (3) This approach can produce a punch shear failure on thick sheet If that type of failure is undesirable, Geometry FC is to be used Geometry FB is suitable for research and development because of the smaller test area required 6.2 As cracks usually start at the surface opposite the one that is struck, the results can be greatly influenced by the quality of the surface of test specimens Therefore, the composition of this surface layer, its smoothness or texture, levels of and type of texture, and the degree of orientation introduced during the formation of the specimen (such as during injection molding) are very important variables Flaws in this surface will also affect results 6.3 Impact properties of plastic materials can be very sensitive to temperature This test can be carried out at any The boldface numbers in parentheses refer to a list of references at the end of the text D5628 − 18 Dimensions of Conical Dart (Not to scale.)—Fig 1(b) NOTE 1—Unless specified, the tolerance on all dimensions shall be 62 % Position A B C D E F R (nose radius) r (radius) S (diameter)A θ A Dimension, mm 27.2 15 12.2 6.4 25.4 12.7 6.35 ± 0.05 Dimension, in 1.07 0.59 0.48 0.25 0.5 0.250 ± 0.002 0.8 6.4 25 ± 1° 0.03 0.25 25 ± 1° Larger diameter shafts shall be used FIG Tup Geometries for Geometries FA (1a), FB (1b), FC (1c), FD (1d), and FE (1e) D5628 − 18 FIG One Type of Falling Mass Impact Tester 7.1.1.1 Contoured specimens shall be firmly held in a jig so that the point of impact will be the same for each specimen 7.1.2 Tup Support, capable of supporting a 13.5-kg (30-lb) mass, with a release mechanism and a centering device to ensure uniform, reproducible drops reasonable temperature and humidity, thus representing actual use environments However, this test method is intended primarily for rating materials under specific impact conditions Apparatus 7.1 Testing Machine—The apparatus shall be constructed essentially as is shown in Fig The geometry of the specimen clamp and tup shall conform to the dimensions given in 7.1.1 and 7.2 7.1.1 Specimen Clamp—For flat specimens, a two-piece annular specimen clamp constructed as shown in Fig is recommended For Geometries FA and FD, the inside diameter shall be 76.0 3.0 mm (3.00 0.12 in.) For Geometry FB, the inside diameter shall be 38.1 0.80 mm (1.5 0.03 in.) For Geometry FC, the inside diameter shall be 127.0 2.5 mm (5.00 0.10 in.) For Geometry FE an annular specimen clamp constructed as shown in Fig is required The inside diameter shall be 40 mm (1.57 0.08 in.) (see Table 1) For Geometries FA, FB, FC, and FD, the inside edge of the upper or supporting surface of the lower clamp shall be rounded slightly; a radius of 0.8 mm (0.03 in.) has been found to be satisfactory For Geometry FE this radius shall be mm (0.04 in.) NOTE 3—Reproducible drops are ensured through the use of a tube or cage within which the tup falls In this event, care should be exercised so that any friction that develops will not reduce the velocity of the tup appreciably 7.1.3 Positioning Device—Means shall be provided for positioning the tup so that the distance from the impinging surface of the tup head to the test specimen is as specified 7.2 Tup: 7.2.1 The tup used in Geometry FA shall have a 15.86 0.10-mm (0.625 0.004-in.) diameter hemispherical head of tool steel hardened to 54 HRC or harder A steel shaft about 13 mm (0.5 in.) in diameter shall be attached to the center of the flat surface of the head with its longitudinal axis at 90° to that surface The length of the shaft shall be great enough to accommodate the maximum mass required (see Fig 1(a) and Table 1) D5628 − 18 FIG Support Plate/Specimen/Clamp Configuration for Geometries FA, FB, FC, and FD FIG Test-Specimen Support for Geometry FE TABLE Tup and Support Ring Dimensions Geometry FA FB FC FD FE 7.2.3 The tup used for Geometry FC shall be made of tool steel hardened to 54 HRC or harder The hemispherical head shall have a diameter of 38.1 0.4 mm (1.5 0.015 in.) A steel shaft about 13 mm (0.5 in.) in diameter shall be attached to the center of the flat surface of the head with its longitudinal axis at 90° to that surface The length of the shaft shall be great enough to accommodate the maximum mass (see Fig 1(c) and Table 1) 7.2.4 The tup used in Geometry FD shall have a 12.70 0.25-mm (0.500 0.010-in.) diameter hemispherical head of tool steel hardened to 54 HRC or harder A steel shaft about mm (0.31 in.) in diameter shall be attached to the center of the flat surface of the head with its longitudinal axis at 90° to the surface The length of the shaft shall be great enough to accommodate the maximum mass required (see Fig 1(d) and Table 1) 7.2.5 The tup used in Geometry FE shall have a 20.0 0.2-mm (0.787 0.008-in.) diameter hemispherical head of tool steel hardened to 54 HRC or harder A steel shaft about 13 Dimensions, mm (in.) Tup Diameter Inside Diameter Support Ring 15.86 ± 0.10 (0.625 ± 0.004) 12.7 ± 0.1 (0.500 ± 0.003) 38.1 ± 0.4 (1.5 ± 0.010) 12.70 ± 0.25 (0.500 ± 0.010) 20.0 ± 0.2 (0.787 ± 0.008) 76.0 ± 3.0 (3.00 ± 0.12) 38.1 ± 0.8 (1.5 ± 0.03) 127.0 ± 2.5 (5.00 ± 0.10) 76.0 ± 3.0 (3.00 ± 0.12) 40.0 ± 2.0 (1.57 ± 0.08) 7.2.2 The tup used in Geometry FB shall be made of tool steel hardened to 54 HRC or harder The head shall have a diameter of 12.76 0.1 mm (0.500 0.003 in.) with a conical (50° included angle) configuration such that the conical surface is tangent to the hemispherical nose A 6.4-mm (0.25-in.) diameter shaft is satisfactory (see Fig 1(b) and Table 1) D5628 − 18 TABLE Minimum Size of Specimen Geometry FA FB FC FD FE ISO 6603-1 the test specimen shall be 60 mm (2.4 0.08 in.) in diameter or 60 mm (2.4 0.08 in.) square with a thickness of 0.1 mm (0.08 0.004 in.) Machining specimens to reduce thickness variation is not permissible Specimen Diameter, mm (in.) Square Specimen, mm (in.) 89 (3.5) 89 by 89 (3.5 by 3.5) 51 (2.0) 51 by 51 (2.0 by 2.0) 140 (5.5) 140 by 140 (5.5 by 5.5) 89 (3.5) 89 by 89 (3.5 by 3.5) 58 (2.3) 58 by 58 (2.3 by 2.3) 10.3 When the approximate mean failure mass for a given sample is known, 20 specimens will usually yield sufficiently precise results If the approximate mean failure mass is unknown, six or more additional specimens shall be used to determine the appropriate starting point of the test For compliance with ISO 6603-1 a minimum of 30 specimens must be tested mm (0.5 in.) in diameter shall be attached to the center of the flat surface of the head with its longitudinal axis at 90° to the surface The length of the shaft shall be great enough to accommodate the maximum mass required (see Fig 1(e) and Table 1) 7.2.6 The tup head shall be free of nicks, scratches, or other surface irregularities 10.4 Carefully examine the specimen visually to ensure that samples are free of cracks or other obvious imperfections or damages, unless these imperfections constitute variables under study Samples known to be defective shall not be tested for specification purposes Production parts, however, shall be tested in the as-received condition to determine conformance to specified standards 7.3 Masses—Cylindrical steel masses are required that have a center hole into which the tup shaft will fit A variety of masses are needed if different materials or thicknesses are to be tested The optimal increments in tup mass range from 10 g or less for materials of low impact resistance, to kg or higher for materials of high impact resistance 10.5 Select a suitable method for making the specimen that will not affect the impact resistance of the material 10.6 Specimens range from having flat smooth surfaces on both sides, being textured on one side and smooth on the other side, or be textured on both surfaces When testing, special attention must be paid to how the specimen is positioned on the support 7.4 Micrometer—Apparatus for measuring the width and thickness of the test specimen shall comply with the requirements of Test Methods D5947 NOTE 4—As few as ten specimens often yield sufficiently reliable estimates of the mean-failure mass However, in such cases the estimated standard deviation will be relatively large (1) 7.5 The mass of the tup head and shaft assembly and the additional mass required must be known to within an accuracy of 61 % 11 Conditioning 11.1 Unless otherwise specified, by contract or relevant ASTM material specification, condition the test specimens in accordance with Procedure A of Practice D618, for those tests where conditioning is required Temperature and humidity tolerances shall be in accordance with Section of Practice D618, unless otherwise specified by contract or relevant ASTM material specification For compliance with ISO requirements, the specimens must be conditioned for a minimum of 16 h prior to testing or post conditioning in accordance with ISO 291, unless the period of conditioning is stated in the relevant ISO specification for the material 11.1.1 Note that for some hygroscopic materials, such as polyamides, the material specifications (for example, Classification System D6779) call for testing “dry as-molded specimens” Such requirements take precedence over the above routine preconditioning to 50 % RH and require sealing the specimens in water vapor-impermeable containers as soon as molded and not removing them until ready for testing Hazards 8.1 Safety Precautions: 8.1.1 Cushioning and shielding devices shall be provided to protect personnel and to avoid damage to the impinging surface of the tup A tube or cage can contain the tup if it rebounds after striking a specimen 8.1.2 When heavy weights are used, it is hazardous for an operator to attempt to catch a rebounding tup Figure of Test Method D2444 shows an effective mechanical “rebound catcher” employed in conjunction with a drop tube Sampling 9.1 Sample the material to meet the requirements of Section 14 10 Test Specimens 10.1 Flat test specimens shall be large enough so that they can be clamped firmly if clamping is desirable See Table for the minimum size of specimen that can be used for each test geometry 11.2 Conduct tests at the same temperature and humidity used for conditioning with tolerances in accordance with Section of Practice D618, unless otherwise specified by contract or relevant ASTM material specification 10.2 The thickness of any specimen in a sample shall not differ by more than % from the average specimen thickness of that sample However, if variations greater than % are unavoidable in a sample that is obtained from parts, the data shall not be used for referee purposes For compliance with 11.3 When testing is desired at temperatures other than 23°C, transfer the materials to the desired test temperature within 30 min, preferably immediately, after completion of the preconditioning Hold the specimens at the test temperature for D5628 − 18 12.12 In this manner, select the impact height or mass for each test from the results observed with the specimen just previously tested Test each specimen only once no more than h prior to test, and, in no case, for less than the time required to ensure thermal equilibrium in accordance with Section 10 of Test Method D618 12.13 For best results, the mass or height increment used shall be equivalent to s, the estimated standard deviation of the test for that sample An increment of 0.5 to times s is satisfactory (see section 13.4) 12 Procedure 12.1 Determine the number of specimens for each sample to be tested, as specified in 10.3 12.2 Mark the specimens and condition as specified in 11.1 NOTE 6—An increment of 10 % of the estimated mean-failure mass or mean-failure height has been found to be acceptable in most instances 12.3 Prepare the test apparatus for the geometry (FA, FB, FC, FD, FE) selected 12.14 Keep a running plot of the data, as shown in Appendix X1 Use one symbol, such as X, to indicate a failure and a different symbol, such as O, to indicate a non-failure at each mass or height level 12.4 Measure and record the thickness of each specimen in the area of impact In the case of injection molded specimens, it is sufficient to measure and record thickness for one specimen when it has been previously demonstrated that the thickness does not vary by more than % 12.15 For any specimen that gives a break behavior that appears to be an outlier, the conditions of that impact shall be examined The specimen shall be discarded only if a unique cause for the anomaly is found, such as an internal flaw visible in the broken specimen Note that break behavior can vary widely within a set of specimens Data from specimens that show atypical behavior shall not be discarded simply on the basis of such behavior 12.5 Choose a specimen at random from the sample 12.6 Clamp or position the specimen The same surface or area shall be the target each time (see 6.2) When clamping is employed, the force shall be sufficient to prevent motion of the clamped portion of the specimen when the tup strikes 12.7 Unless otherwise specified, initially position the tup 0.660 0.008 m (26.0 0.3 in.) from the surface of the specimen 13 Calculation 13.1 Mean-Failure Mass—If a constant-height procedure was used, calculate the mean-failure mass from the test data obtained, as follows: 12.8 Adjust the total mass of the tup or the height of the tup, or both, to that amount expected to cause half the specimens to fail w w o 1d w ~ A/N60.5! NOTE 5—If failures cannot be produced with the maximum available missile mass, the drop height can be increased The test temperature could be reduced by (a) use of an ice-water mixture, or (b) by air-conditioned environment to provide one of the temperatures given in 3.3 of Test Methods D618 Conversely, if the unloaded tup causes failures when dropped 0.660 m, the drop height can be decreased A moderate change in dart velocity will not usually affect the mean-failure energy appreciably Refer to 5.1 (1) 13.2 Mean-Failure Height—If a constant-mass procedure was used, calculate the mean-failure height from the test data obtained, as follows: h h o 1d h ~ A/N60.5! (2) where: w = h = dw = dh = N = 12.9 Release the tup Be sure that it hits the center of the specimen If the tup bounces, catch it to prevent multiple impact damage to the specimen’s surface (see 8.1.2) 12.10 Remove the specimen and examine it to determine whether or not it has failed Permanent deformation alone is not considered failure, but note the extent of such deformation (depth, area) For some polymers, for example, glassreinforced polyester, incipient cracking is difficult to determine with the naked eye Exposure of the stressed surface to a penetrating dye, such as gentian violet, confirms the onset of cracking As a result of the wide range of failure types observed with different materials, the definition of failure defined in the material specification, or a definition agreed upon by supplier and user, shall take precedence over the definition stated in 3.2.1 wo ho A mean-failure mass, kg, mean-failure height, mm, increment of tup weight, kg, increment of tup height, mm, total number of failures or non-failures, whichever is smaller For ease of notation, call whichever are used events, = smallest mass at which an event occurred, kg = lowest height at which an event occurred, mm (or in.), = k in , i ni wi hi = = = = ( i50 i 0, 1, k (counting index, starts at ho or wo), number of events that occurred at hi or wi, wo + idw, and ho + idh In calculating w or h, the negative sign is used when the events are failures The positive sign is used when the events are non-failures Refer to the example in Appendix X1 12.11 If the first specimen fails, remove one increment of mass from the tup while keeping the drop height constant, or decrease the drop height while keeping the mass constant (see 12.12) If the first specimen does not fail, add one increment of mass to the tup or increase the drop height one increment, as above Then test the second specimen 13.3 Mean-Failure Energy—Compute the mean-failure energy as follows: MFE = hwf where: MFE = mean-failure energy, J, D5628 − 18 h w f Use f TABLE Precision, Method FB = mean-failure height or constant height as applicable, mm = mean-failure mass or constant mass as applicable, kg, and = factor for conversion to joules = 9.80665 × 10−3 if h = mm and w = kg Material Polymethyl Methacrylate (PMMA) Styrene–Butadiene (SB)A Acrylonitrile–Butadiene–Styrene (ABS)A 13.4 Estimated Standard Deviation of the Sample—If desired for record purposes, the estimated standard deviation of the sample for either variable mass or variable height can be calculated as follows: s w 1.62d w @ B/N ~ A/N ! # 10.047d w or s h 1.62d h @ B/N ~ A/N ! # 10.047d h A ( k i50 (4) i 2n i (5) The above calculation is valid for [B/N − (A/N) ] > 0.3 If the value is